1. Field of the Invention
The present invention relates to an original carrying apparatus which scans an original being moved.
2. Related Background Art
Conventionally, a method of moving an original in a state that a reader unit (i.e., exposure lamp) is kept still, thereby reading (or exposure scanning) the original has been known. This method is referred to as running reading. In this case a general analog copy machine performs the exposure scanning on the original by moving the exposure lamp from left to right when the original has been put on a platen glass. In a case where the running reading is performed by the analog copy machine, the original is moved from right to left such that a copy image does not become a mirror image (or reflected image). FIG. 46 shows a structure to perform the running reading in the conventional analog copy machine.
When the running reading is performed, the exposure lamp is kept still at a position shown in FIG. 46, and the original is moved by a belt B1 to be exposed. In this case, a distance between an antecedent original Dn-1 and a subsequent original Dn is controlled to be L1 when these originals are being held by the belt B1. In the running reading, driving of the belt B1 is stopped every time original exposure for one paper sheet terminates, and FIG. 46 shows such a state. The distance L1 is the sum of distances L6 and L5. The distance L6 is the distance which is necessary to perform an operation until rotational speed of the belt B1 is reduced to zero after a trailing edge of the original Dn-1 passes through the exposure lamp, and the distance L5 is the distance which is necessary to perform an operation to accelerate the rotational speed of the stopped belt B1 so as to reach a stable running reading speed.
The distance between the originals Dn-1 and Dn both held by the belt B1 must be established before the original Dn is held by the belt B1. In the conventional analog copy machine, before the once-stopped belt B1 again starts, a next original Dn+1 is carried such that the original Dn+1 reaches a position separated from the original Dn by the distance L1. When the running reading of the document Dn starts, rollers R1 and R2 start rotating in synchronism with the belt B1, and the document Dn+1 is carried to the belt B1 as the distance L1 between the documents Dn and Dn+1 is maintained.
At a time when the document Dn+1 is at the position shown in FIG. 46, a pair of separation rollers R4 is arranged to be apart from the document Dn+1 by a distance L2 such that the document Dn+1 does not get in contact with the rollers R4, because of the following reason. That is, since one of the rollers R4 is rotated in a direction opposite to an original carrying direction, carrying speed of the original is unstable while the rollers R4 hold the original. Thus, when the rollers R1 and R2 and the belt B1 synchronously start moving, if the rollers R4 are still holding the document Dn+1, the distance L1 between the documents Dn and Dn+1 can not be maintained.
As described above, in the conventional analog copy machine, the distance (distance L1+length of one sheet of original+distance L2) is necessary as the distance from a trailing edge of the document Dn to the rollers R4, whereby a long original carrying path has been necessary. For this reason, it has been an obstacle to the downsizing of the copy machine.